Organic electroluminescent device

ABSTRACT

An organic electroluminescent device comprising: a pair of electrodes; and at least one organic compound layer including a light emitting layer between the pair of electrodes, wherein the organic compound layer contains a metal complex that has a tridentate or more ligand and two or more metal ions.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an organic electroluminescent device(EL device) which can emit light by converting electric energy intooptical energy.

2. Description of the Related Art

Since an organic electroluminescent device can emit high-brightnesslight with a low voltage, the organic electroluminescent device hasattracted attentions as a promising display device. External quantumefficiency is an important characteristic of the organicelectroluminescent device. The external quantum efficiency is calculatedas “external quantum efficiency Φ=the number of photons emitted from adevice/the number of electrons injected into the device,” and it can besaid that it is more advantageous in view of power consumption as theexternal quantum efficiency becomes greater.

The external quantum efficiency of the organic electroluminescent deviceis defined by “external quantum efficiency Φ=internal quantumefficiency×light extraction efficiency.” In an organicelectroluminescent device using fluorescent light emission from anorganic compound, since the limit value of the internal quantumefficiency is about 25% and the light extraction efficiency is about20%, the limit value of the external quantum efficiency is about 5%.

A technology, which can enhance the internal quantum efficiency of anorganic electroluminescent by the use of a triplet light emittingmaterial (phosphorescent material) including a platinum complex andenhance the external quantum efficiency in comparison with aconventional device (singlet light emitting device) using fluorescentlight emission, is disclosed in WO 2004/108857

SUMMARY OF THE INVENTION

In the organic electroluminescent device described in WO 2004/108857,the external quantum efficiency could be improved, but improvement indurability has been required. There is requirement for furtherimprovement in external quantum efficiency.

An object of the present invention is to provide an organicelectroluminescent device having high external quantum efficiency andexcellent light emission efficiency.

The above-mentioned object is accomplished by the following means.

(1) An organic electroluminescent device comprising:

a pair of electrodes; and

at least one organic compound layer including a light emitting layerbetween the pair of electrodes,

wherein the at least one organic compound layer contains a metal complexthat has a tridentate or more ligand and two or more metal ions.

(2) The organic electroluminescent device as described in (1) above,

wherein the metal complex is a phosphorescent material.

(3) The organic electroluminescent device as described in (1) or (2)above,

wherein the tridentate or more ligand of the metal complex is a ligandin which two quadridentate ligands are connected to each other.

(4) The organic electroluminescent device as described in any of (1) to(3) above,

wherein the two or more metal ions of the metal complex are selectedfrom the group consisting of a rhodium ion, a palladium ion, a rheniumion, a iridium ion and a platinum ion.

(5) The organic electroluminescent device as described in any of (1) to(4) above,

wherein the metal complex is a compound represented by Formula (1)

wherein M¹¹ and M¹² each independently represents a metal ion;

Q¹¹, Q¹², Q¹³ and Q¹⁴ each independently represents an atom groupcoordinating with M¹¹;

Q¹⁵, Q¹⁶, Q¹⁷ and Q¹⁸ each independently represents an atom groupcoordinating with M¹²;

L¹¹, L¹², L¹³, L¹⁴, L¹⁵ and L¹⁶ each independently represents a singlebond or a connection group;

L¹⁷ represents a connection group;

n¹¹ and n¹² each independently represents 0 or 1, provided that when n¹¹is 0, a bond in which L¹³ is interposed between Q¹³ and Q¹⁴ does notexist, and when n¹² is 0, a bond in which L¹⁶ is interposed between Q¹⁷and Q¹⁸ does not exist;

M¹¹-Q¹¹ bond, M¹¹-Q¹² bond, M¹¹-Q¹³ bond, M¹¹-Q¹⁴ bond, M¹²-Q¹⁵ bond,M¹²-Q¹⁶ bond, M¹²-Q¹⁷ bond and M¹²-Q¹⁸ bond each may be a covalent bond,a coordinate bond or an ion bond.

(6) The organic electroluminescent device as described in (5) above,

wherein the compound represented by Formula (1) is a compoundrepresented by Formula (2) or (3):

In Formula (2), M²¹ and M²² each independently represents a metal ion;

Q²¹, Q²², Q²³ and Q²⁴ each independently represents an atom groupcoordinating with M²¹;

Q²⁵, Q²⁶, Q²⁷ and Q²⁸ each independently represents an atom groupcoordinating with M²²;

L²¹, L²², L²³, L²⁴, L²⁵ and L²⁶ each independently represents a singlebond or a connection group;

L²⁷ represents a connection group;

n₂₁ and n²² each independently represents 0 or 1, provided that when n²¹is 0, a bond in which L²³ is interposed between Q²³ and Q²⁴ does notexist, and when n²² is 0, a bond in which L²⁶ is interposed between Q²⁷and Q²⁸ does not exist;

M²¹-Q²¹ bond, M²¹-Q22 bond, M²²-Q²⁵ bond and M²²-Q²⁶ bond (dotted line)represent coordinate bonds; and

M²¹-Q²³ bond, M²¹-Q²⁴ bond, M²²-Q²⁷ bond and M²²-Q²⁸ bond each may be acovalent bond, a coordinate bond or an ion bond, and

in Formula (3), M³¹ and M³² each independently represents a metal ion;

Q³¹, Q³², Q³³ and Q³⁴ each independently represents an atom groupcoordinating with M³¹;

Q³⁵, Q³⁶, Q³⁷ and Q³⁸ each independently represents an atom groupcoordinating with M³²;

L³¹, L³², L³³, L³⁴, L³⁵ and L³⁶ each independently represents a singlebond or a connection group;

L³⁷ represents a connection group;

n³¹ and n³² each independently represents 0 or 1, provided that when n³¹is 0, a bond in which L³³ is interposed between Q³³ and Q³⁴ does notexist, and when n³² is 0, a bond in which L³⁶ is interposed between Q³⁷and Q³⁸ does not exist;

M³¹-Q³³ bond, M³¹-Q³⁴ bond, M³²-Q³⁷ bond and M³²-Q³⁸ bond (dotted line)represent coordinate bonds; and

M³¹-Q³¹ bond, M³¹-Q³² bond, M³²-Q³⁵ bond and M³²-Q³⁶ bond each may be acovalent bond, a coordinate bond or an ion bond.

(7) The organic electroluminescent device as described in (5) above,

wherein the compound represented by Formula (1) is a compoundrepresented by Formula (4):

wherein M⁴¹ and M⁴² each independently represents a metal ion;

Q⁴³ and Q⁴⁴ each independently represents an atom group coordinatingwith M⁴¹;

Q⁴⁷ and Q⁴⁸ each independently represents an atom group coordinatingwith M⁴²;

L⁴⁷ represents a connection group;

R⁴¹, R⁴², R⁴³ and R⁴⁴ each independently represents a substituent group;

m⁴¹, m⁴², m⁴³ and m⁴⁴ each independently represents an integer of 0 to3;

M⁴¹-N bond and M⁴²-N bond (dotted line) represent coordinate bonds; and

M⁴¹-Q⁴³ bond, M⁴¹-Q⁴⁴ bond, M⁴²-Q⁴⁷ bond and M⁴²-Q⁴⁸ bond each may be acovalent bond, a coordinate bond or an ion bond.

DETAILED DESCRIPTION OF THE INVENTION

An organic electroluminescent device according to the present inventionhas at least one organic compound layer including a light emitting layerbetween a pair of electrodes, and the organic compound layer contains ametal complex having a tridentate or more ligand and two or more metalions.

The metal complex is preferably a phosphorescent material.

The phosphorescent quantum yield of the phosphorescent material ispreferably 30% or more, more preferably 50% or more, still morepreferably 70% or more, and most preferably 90% or more.

The phosphorescent quantum yield of the phosphorescent material can bemeasured by freezing and degassing the phosphorescent material (forexamples, a concentration of 1×10³ mol/l) dissolved in an organicsolvent (such as toluene and dichloroethane) and then comparing theamount of light emission resulting from irradiation of light at a roomtemperature with that of a material (such as fluorescein, anthracene,and rhodamine) of which the absolute fluorescent quantum yield is known.

The life time of the phosphorescent light emitted from thephosphorescent material is preferably 10 μs or less, more preferably 5μs or less, and most preferably 3 μs or less.

The life time of the phosphorescent light emitted from thephosphorescent material can be obtained by freezing and degassing thephosphorescent material (for examples, a concentration of 1×10⁻³ mol/l)dissolved in an organic solvent (such as toluene and dichloroethane) andthen measuring the life time of light generated by irradiation of lightat a room temperature.

The metal complex has preferably two or more metal ions, and morepreferably two metal ions. The metal ions includes preferably atransition metal ion, more preferably one of a ruthenium ion, a rhodiumion, a palladium ion, a silver ion, a tungsten ion, a rhenium ion, anosmium ion, an iridium ion, a platinum ion, and a gold ion, still morepreferably one of a rhodium ion, a palladium ion, a rhenium ion, aniridium ion, and a platinum ion, still more preferably one of a platinumion and a palladium ion, and most preferably a platinum ion.

The metal complex has preferably tridentate or more ligand and morepreferably quadridentate or more ligand. The metal complex haspreferably two or more tridentate or more ligands and more preferably aligand in which two quadridentate ligands are connected to each other.

The ligand is not particularly limited as long as it is an atom groupcoordinating with the metal ions. Examples of the ligand can include anatom group coordinating with a carbon atom, an atom group coordinatingwith a nitrogen atom, an atom group coordinating with an oxygen atom, anatom group coordinating with a sulfur ion, and an atom groupcoordinating with a phosphorous ion, and the atom group coordinatingwith a carbon atom and the atom group coordinating with a nitrogen atomare more preferable.

Examples of the coordinate bond between the metal ion and the ligand caninclude a coordinate bond, a covalent bond, and an ion bond.

The metal complex may be a low-molecular compound, or may be an oligomercompound or a polymer compound having a complex in a main chain or aside chain, and is preferably the low-molecular compound. When the metalcomplex is the polymer compound, the weight-average molecular weight (inpolystyrene equivalent) is preferably in the range of 1,000 to5,000,000, more preferably in the range of 2,000 to 1,000,000, and stillmore preferably in the range of 3,000 to 100,000.

It is preferable that the metal complex is a compound represented byFormula (1).

In Formula (1), M¹¹ and M¹² each independently represents a metal ion.M¹¹ and M¹² may be the same or different from each other, and preferablyM¹¹ and M¹² are the same. The metal ion is preferably a transition metalion, more preferably one of a ruthenium ion, a rhodium ion, a palladiumion, a silver ion, a tungsten ion, a rhenium ion, an osmium ion, aniridium ion, a platinum ion, and a gold ion, still more preferably oneof a rhodium ion, a palladium ion, a rhenium ion, an iridium ion, and aplatinum ion, still more preferably one of a platinum ion and apalladium ion, and most preferably a platinum ion.

Q¹¹, Q¹², Q¹³, and Q¹⁴ represent atom groups (ligands) coordinating withM¹¹ and Q¹⁵, Q¹⁶, Q¹⁷, and Q¹⁸ represent atom groups (ligands)coordinating with M¹², respectively.

Q¹¹, Q¹², Q¹³, and Q¹⁴ are not particularly limited as long as they areatom groups coordinating with M¹¹, but are preferably one of an atomgroup coordinating with a carbon atom, an atom group coordinating with anitrogen atom, an atom group coordinating with an oxygen atom, an atomgroup coordinating with a sulfur ion, and an atom group coordinatingwith a phosphorous ion, more preferably one of an atom groupcoordinating with a carbon atom, an atom group coordinating with anitrogen atom, and an atom group coordinating with an oxygen atom, andstill more preferably one of an atom group coordinating with a carbonatom and an atom group coordinating with a nitrogen atom.

Q¹⁵, Q¹⁶, Q¹⁷, and Q¹⁸ are not particularly limited as long as they areatom groups coordinating with M¹², but are preferably one of an atomgroup coordinating with a carbon atom, an atom group coordinating with anitrogen atom, an atom group coordinating with an oxygen atom, an atomgroup coordinating with a sulfur ion, and an atom group coordinatingwith a phosphorous ion, more preferably one of an atom groupcoordinating with a carbon atom, an atom group coordinating with anitrogen atom, and an atom group coordinating with an oxygen atom, andstill more preferably one of an atom group coordinating with a carbonatom and an atom group coordinating with a nitrogen atom.

Examples of the atom group coordinating with a carbon atom can includean imino group, an aromatic hydrocarbon cyclic group (benzene,naphthalene, and the like), a heterocyclic group (thiophene, pyridine,pyrazine, pyrimidine, pyridazine, triazine, thiazole, oxazole, pyrrole,imidazole, pyrazole, triazole, and the like), condensed rings includingthe groups, and tautomers thereof. These groups may additionally have asubstituent group. Examples of the substituent group can include groupsto be described with reference to R⁴¹.

Examples of the atom group coordinating with a nitrogen atom can includean nitrogen-containing heterocyclic group (pyridine, pyrazine,pyrimidine, pyridazine, triazine, thiazole, oxazole, pyrrole, imidazole,pyrazole, triazole, and the like), an amino group (alkyl amino group(which has preferably a carbon number of 2 to 30, more preferably acarbon number of 2 to 20, and most preferably a carbon number of 2 to10, and an example of which is methyl amino), an aryl amino group (anexample of which is phenyl amino), and the like), an acyl amino group(which has preferably a carbon number of 2 to 30, more preferably acarbon number of 2 to 20, and most preferably a carbon number of 2 to10, and examples of which can include acetyl amino and benzoyl amino),an alkoxycarbonyl amino group (which has preferably a carbon number of 2to 30, more preferably a carbon number of 2 to 20, and most preferably acarbon number of 2 to 10, and an example of which is methoxycarbonylamino), an aryloxycarbonyl amino group (which has preferably a carbonnumber of 7 to 30, more preferably a carbon number of 7 to 20, and mostpreferably a carbon number of 7 to 12, and an example of which isphenyloxycarbonyl amino), a sulfonyl amino group (which has preferably acarbon number of 1 to 30, more preferably a carbon number of 1 to 20,and most preferably a carbon number of 1 to 12, and examples of whichcan include methansulfonyl amino and benzensulfonyl amino), and an aminogroup. These groups may be substituted again. Examples of thesubstituent group can include the groups to be described later withreference to R⁴¹.

Examples of the atom group coordinating with an oxygen atom can includean alkoxy group (which has preferably a carbon number of 1 to 30, morepreferably a carbon number of 1 to 20, and most preferably a carbonnumber of 1 to 10, and examples of which can include methoxy, ethoxy,buthoxy, and 2-ethylhexyloxy), an aryloxy group (which has preferably acarbon number of 6 to 30, more preferably a carbon number of 6 to 20,and most preferably a carbon number of 6 to 12, and examples of whichcan include phenyloxy, 1-naphthaloxy, and 2-naphthaloxy), and aheterocyclic oxy group (which has preferably a carbon number of 1 to 30,more preferably a carbon number of 1 to 20, and most preferably a carbonnumber of 1 to 12, and examples of which can include pyridyloxy,pyrazyloxy, pyrimidyloxy, and quinolyloxy), an acyloxy group (which haspreferably a carbon number of 2 to 30, more preferably a carbon numberof 2 to 20, and most preferably a carbon number of 2 to 10, and examplesof which can include acetoxy and benzoyloxy), a silyloxy group (whichhas preferably a carbon number of 3 to 40, more preferably a carbonnumber of 3 to 30, and most preferably a carbon number of 3 to 24, andexamples of which can include trimethylsilyloxy and triphenylsilyloxy),a carbonyl group (examples of which can include a ketone group, an estergroup, and an amide group), an ether group (examples of which caninclude a dialkylether group, a diarylether group, and a furyl group).These groups may be substituted again. Examples of the substituent groupcan include the groups to be described later with reference to R⁴¹.

Examples of the atom group coordinating with an sulfur atom can includean alkylthio group (which has preferably a carbon number of 1 to 30,more preferably a carbon number of 1 to 20, and most preferably a carbonnumber of 1 to 12, and examples of which can include methylthio andethylthio), a arylthio group (which has preferably a carbon number of 6to 30, more preferably a carbon number of 6 to 20, and most preferably acarbon number of 6 to 12, and examples of which can include phenylthio),a heterocyclic thio group (which has preferably a carbon number of 1 to30, more preferably a carbon number of 1 to 20, and most preferably acarbon number of 1 to 12, and examples of which can include pyridylthioand 2-benzthiazolyl), a thiocarbonyl group (examples of which caninclude a thioketone group and a thioester group), and a thioether group(examples of which can include a dialkylthioether group, adiarylthioether group, and a thiofuryl group). These groups may besubstituted again. Examples of the substituent group can include thegroups to be described with reference to R⁴¹ later.

Examples of the atom group coordinating with a phosphorus atom caninclude a dialkylphosphino group, a diarylphosphino group,trialkylphosphine, triarylphosphine, and a phosphinine group. Thesegroups may be substituted again. Examples of the substituent group caninclude the groups to be described later with reference to R⁴¹.

Q¹¹, Q¹², Q¹⁵ and Q¹⁶ can include preferably one of an atom groupcoordinating with a nitrogen atom, an atom group coordinating with anoxygen atom, and an atom group coordinating with a phosphorus atom, morepreferably an atom group coordinating with a nitrogen atom, still morepreferably a nitrogen-containing heterocyclic group coordinating with anitrogen atom, and most preferably a monocyclic nitrogen-containingheterocyclic group coordinating with a nitrogen atom.

Q¹³, Q¹⁴, Q¹⁷, and Q¹⁸ can include preferably one of an atom groupcoordinating with a carbon atom, an atom group coordinating with anitrogen atom, and an atom group coordinating with an oxygen atom, morepreferably one of an aryl group coordinating with a carbon atom, aheteroaryl group coordinating with a carbon atom, a heteroaryl groupcoordinating with a nitrogen atom, a carboxyl group coordinating with anoxygen group, an aryloxy group coordinating with an oxygen atom, and aheteroaryloxy group coordinating with an oxygen atom, still morepreferably one of an aryl group coordinating with a carbon atom, aheteroaryl group coordinating with a carbon atom, a heteroaryl groupcoordinating with a nitrogen atom, and a carboxyl group coordinatingwith an oxygen atom, and most preferably one of an aryl groupcoordinating with a carbon atom and a heteroaryl group coordinating witha carbon atom.

L¹¹, L¹², L¹³, L¹⁴, L¹⁵, and L¹⁶ represent single bonds or connectiongroups. The connection groups are not particularly limited, but examplesthereof can include an alkylene group (examples of which can include amethylene group, a dimethylene group, a diisopropylmethylene group, adiphenylmethylene group, an ethylene group, and a tetramethylethylenegroup), an alkenylene group (examples of which can include a vinylenegroup and a dimethylvinylene group), an alkinylene group (examples ofwhich can include an ethinylene group), an arylene group (examples ofwhich can include a phenylene group and a naphthalene group), aheteroarylene group (examples of which can include a pyridylene group, apyrazylene group, and a quinolylene group), an oxygen connection group,a sulfur connection group, a nitrogen connection group (examples ofwhich can include a methylamino connection group, a phenylaminoconnection group, and a t-butylamino connection group), a siliconconnection group, and connection groups in which the connection groupsare combined (examples of which can include an oxylenemethylene group).

L¹¹, L¹², L¹⁴, and L¹⁵ include preferably one of a single bond, analkylene group, and an oxygen connection group, more preferably one of asignal bond and an alkylene group, and most preferably a single bond.

L¹³ and L¹⁶ include preferably one of a single bond, an alkylene group,an oxygen connection group, and a nitrogen connection group, morepreferably one of an alkylene connection group and an oxygen connectiongroup, and most preferably an alkylene connection group.

L¹⁷ includes a four-valence or more connection group. L¹³ includespreferably one of a carbon connection group, a silicon connection group,an alkenyl connection group, an aryl connection group, a heteroarylconnection group, and a connection group obtained by combining them,more preferably one of a carbon connection group and a siliconconnection group, and most preferably a carbon connection group.

n¹¹ and n¹² represent 0 or 1. When n¹¹ is 0, a bond in which L¹³ isinterposed between Q¹³ and Q¹⁴ does not exist. When n¹² is 0, a bond inwhich L¹⁶ is interposed between Q¹⁷ and Q¹⁸ does not exist. n¹¹ and n¹²are preferably 0.

The M¹¹-Q¹¹ bond, the M¹¹-Q¹² bond, the N¹¹-Q¹³ bond, the M¹¹-Q¹⁴ bond,the M¹²-Q¹⁵ bond, the N¹²-Q¹⁶ bond, the M¹²-Q¹⁷ bond, and the M¹²-Q¹⁸bond may be one of a covalent bond, a coordinate bond, and an ion bond.

The M¹¹-Q¹¹ bond, the M¹¹-Q¹² bond, the M¹¹-Q¹⁵ bond, and the M¹¹-Q¹⁶bond are preferably a coordinate bond. The M¹¹-Q¹³ bond, the M¹¹-Q¹⁴bond, the M¹¹-Q¹⁷ bond, and the M¹¹-Q¹⁸ bond are preferably one of acovalent bond and an ion bond, and more preferably a covalent bond.

The compound represented by Formula (1) is preferably a compoundrepresented by Formula (2) or (3), more preferably a compoundrepresented by Formula (2), and most preferably a compound representedby Formula (4).

Formula (2) is now explained. M²¹ and M²² are the same as M¹¹ describedabove and the preferable ranges thereof are also the same. M²¹ and M²²may be the same or different from each other, and preferably M²¹ and M²²are the same. Q²¹, Q²², Q²³, and Q²⁴ represent atom groups coordinatingwith M²¹ and Q²⁵, Q²⁶, Q²⁷, and Q²⁸ represent atom groups coordinatingwith M²².

Q²¹, Q²², Q²⁵ and Q²⁶ are preferably one of an atom group coordinatingwith a nitrogen atom, an atom group coordinating with an oxygen atom,and an atom group coordinating with a phosphorus atom, more preferablyan atom group coordinating with a nitrogen atom, still more preferably anitrogen-containing heterocyclic group coordinating with a nitrogenatom, and most preferably a monocyclic nitrogen-containing heterocyclicgroup coordinating with a nitrogen atom.

Q²³, Q²⁴, Q²⁷ and Q²⁸ are preferably one of an atom group coordinatingwith a carbon atom, an atom group coordinating with a nitrogen atom, andan atom group coordinating with an oxygen atom, more preferably one ofan aryl group coordinating with a carbon atom, a heteroaryl groupcoordinating with a carbon atom, a heteroaryl group coordinating with anitrogen atom, a carboxyl group coordinating with an oxygen group, anaryloxy group coordinating with an oxygen atom, and a heteroaryloxygroup coordinating with an oxygen atom, still more preferably one of anaryl group coordinating with a carbon atom, a heteroaryl groupcoordinating with a carbon atom, a heteroaryl group coordinating with anitrogen atom, and a carboxyl group coordinating with an oxygen atom,and most preferably one of an aryl group coordinating with a carbon atomand a heteroaryl group coordinating with a carbon atom.

L²¹, L²², L²³, L²⁴, L²⁵, L²⁶, and L²⁷ are the same as L¹¹, L¹², L¹³,L¹⁴, L¹⁵, L¹⁶, and L¹⁷ described above, and the preferable rangesthereof are also the same.

n²¹ and n²² represent 0 or 1. When n²¹ is 0, a bond in which L²³ isinterposed between Q²³ and Q²⁴ does not exist. When n²² is 0, a bond inwhich L²⁶ is interposed between Q²⁷ and Q²⁸ does not exist. N²¹ and n²²are preferably 0.

Formula (3) is now explained. M³¹ and M³² are the same as M¹¹ describedabove and the preferable ranges thereof are also the same. M³¹ and M³²may be the same or different from each other, and preferably M³¹ and M³²are the same.

Q³¹, Q³², Q³³, and Q³⁴ represent atom groups coordinating with M³¹ andQ³⁵, Q³⁶, Q³⁷, and Q³⁸ represent atom groups coordinating with M³².

Q³¹, Q³², Q³⁵ and Q³⁶ are preferably one of an atom group coordinatingwith a carbon atom and an atom group coordinating with a nitrogen atom,more preferably one of an aryl group coordinating with a carbon atom, aheteroaryl group coordinating with a carbon atom, and a heteroaryl groupcoordinating with a nitrogen atom, still more preferably one of an arylgroup coordinating with a carbon atom and a heteroaryl groupcoordinating with a carbon atom, and most preferably an aryl groupcoordinating with a carbon atom.

Q³³, Q³⁴, Q³⁷ and Q³⁸ are preferably one of an atom group coordinatingwith a nitrogen atom, an atom group coordinating with an oxygen atom,and an atom group coordinating with a phosphorus atom, more preferablyan atom group coordinating with a nitrogen atom, still more preferably anitrogen-containing heterocyclic group coordinating with a nitrogenatom, and most preferably a monocyclic nitrogen-containing heterocyclicgroup coordinating with a nitrogen atom.

L³¹, L³², L³³, L³⁴, L³⁵, L³⁶, and L³⁷are the same as L¹¹, L¹², L¹³, L¹⁴,L¹⁵, L¹⁶, and L¹⁷ described above, and the preferable ranges thereof arealso the same.

n³¹ and n³² represent 0 or 1. When n³¹ is 0, a bond in which L³³ isinterposed between Q³³ and Q³⁴ does not exist. When n³² is 0, a bond inwhich L³⁶ is interposed between Q³⁷ and Q³⁸ does not exist. n³¹ and n³²are preferably 0.

Formula (4) is now explained. M⁴¹ and M⁴² are the same as M¹¹ describedabove and the preferable ranges thereof are also the same. M⁴¹ and M⁴²may be the same or different from each other, and preferably M⁴¹ and M⁴²are the same.

Q⁴³, and Q⁴⁴ represent atom groups coordinating with M⁴¹ and Q⁴⁷, andQ⁴⁸ represent atom groups coordinating with M⁴². Q⁴³, Q⁴⁴, Q⁴⁷ and Q⁴⁸are preferably one of an atom group coordinating with a carbon atom andan atom group coordinating with a nitrogen atom, more preferably one ofan aryl group coordinating with a carbon atom, a heteroaryl groupcoordinating with a carbon atom, and a heteroaryl group coordinatingwith a nitrogen atom., still more preferably one of an aryl groupcoordinating with a carbon atom and a heteroaryl group coordinating witha carbon atom, and most preferably an aryl group coordinating with acarbon atom.

L⁴⁷ is the same as L¹⁷ described above, and the preferable range thereofis also the same.

R⁴¹, R⁴², R⁴³, and R⁴⁴ represent substituent groups. Examples of thesubstituent groups can include an alkyl group (which has preferably acarbon number of 1 to 30, more preferably a carbon number of 1 to 20,and most preferably a carbon number of 1 to 10, and examples of whichcan include methyl, ethyl, iso-propyl, tert-butyl, n-octyl, n-decyl,n-hexadecyl, cyclopropyl, cyclopentyl, and cyclohexyl), an alkenyl group(which has preferably a carbon number of 2 to 30, more preferably acarbon number of 2 to 20, and most preferably a carbon number of 2 to10, and examples of which can include vinyl, aryl, 2-butenyl, and3-pentenyl), an alkinyl group (which has preferably a carbon number of 2to 30, more preferably a carbon number of 2 to 20, and most preferably acarbon number of 2 to 10, and examples of which can include propargyland 3-pentinyl), an aryl group (which has preferably a carbon number of6 to 30, more preferably a carbon number of 6 to 20, and most preferablya carbon number of 6 to 12, and examples of which can include phenyl,p-methylphenyl, naphthyl, and anthranil), an amino group (which haspreferably a carbon number of 0 to 30, more preferably a carbon numberof 0 to 20, and most preferably a carbon number of 0 to 10, and examplesof which can include amino, methyl amino, dimethyl amino, diethyl amino,dibenzyl amino, diphenyl amino, and ditolyl amino), an alkoxy group(which has preferably a carbon number of 1 to 30, more preferably acarbon number of 1 to 20, and most preferably a carbon number of 1 to10, and examples of which can include methoxy, ethoxy, butoxy, and2-ethylhexyloxy), an aryloxy group (which has preferably a carbon numberof 6 to 30, more preferably a carbon number of 6 to 20, and mostpreferably a carbon number of 6 to 12, and examples of which can includephenyloxy, 1-naphtayloxy, and 2-naphthyloxy), a heterocyclic oxy group(which has preferably a carbon number of 1 to 30, more preferably acarbon number of 1 to 20, and most preferably a carbon number of 1 to12, and examples of which can include pyridyloxy, pyrazyloxy,pyrimidyloxy, and quinolyloxy), an acyl group (which has preferably acarbon number of 1 to 30, more preferably a carbon number of 1 to 20,and most preferably a carbon number of 1 to 12, and examples of whichcan include acetyl, benzoyl, formyl, and pivaloyl), an alkoxycarbonylgroup (which has preferably a carbon number of 2 to 30, more preferablya carbon number of 2 to 20, and most preferably a carbon number of 2 to12, and examples of which can include methoxycarbonyl andethoxycarbonyl), an aryloxycarbonyl group (which has preferably a carbonnumber of 7 to 30, more preferably a carbon number of 7 to 20, and mostpreferably a carbon number of 7 to 12, and examples of which can includephenyloxycarbonyl), an acyloxy group (which has preferably a carbonnumber of 2 to 30, more preferably a carbon number of 2 to 20, and mostpreferably a carbon number of 2 to 10, and examples of which can includeacetoxy and benzoyloxy), an acyl amino group (which has preferably acarbon number of 2 to 30, more preferably a carbon number of 2 to 20,and most preferably a carbon number of 2 to 10, and examples of whichcan include acetyl amino and benzoyl amino), an alkoxycarbonyl aminogroup (which has preferably a carbon number of 2 to 30, more preferablya carbon number of 2 to 20, and most preferably a carbon number of 2 to12, and examples of which can include methoxycarbonyl amino), anaryloxycarbonyl amino group (which has preferably a carbon number of 7to 30, more preferably a carbon number of 7 to 20, and most preferably acarbon number of 7 to 12, and examples of which can includephenyloxycarbonyl amino), a sulfonyl amino group (which has preferably acarbon number of 1 to 30, more preferably a carbon number of 1 to 20,and most preferably a carbon number of 1 to 12, and examples of whichcan include methane sulfonyl amino and benzene sulfonyl amino), asulfamoyl group (which has preferably a carbon number of 0 to 30, morepreferably a carbon number of 0 to 20, and most preferably a carbonnumber of 0 to 12, and examples of which can include sulfamoyl,methylsulfamoyl, dimethylsulfamoyl, and phenylsulfamoyl), a carbamoylgroup (which has preferably a carbon number of 1 to 30, more preferablya carbon number of 1 to 20, and most preferably a carbon number of 1 to12, and examples of which can include carbamoyl, methylcarbamoyl,diethylcarbamoyl, and phenylcarbamoyl), an alkylthio group (which haspreferably a carbon number of 1 to 30, more preferably a carbon numberof 1 to 20, and most preferably a carbon number of 1 to 12, and examplesof which can include methylthio and ethylthio), an arylthio group (whichhas preferably a carbon number of 6 to 30, more preferably a carbonnumber of 6 to 20, and most preferably a carbon number of 6 to 12, andexamples of which can include phenylthio), a heterocyclic thio group(which has preferably a carbon number of 1 to 30, more preferably acarbon number of 1 to 20, and most preferably a carbon number of 1 to12, and examples of which can include pyridylthio, 2-benzimizolylthio,2-benzoxazolylthio, and 2-benzthiazolylthio), a sulfonyl group (whichhas preferably a carbon number of 1 to 30, more preferably a carbonnumber of 1 to 20, and most preferably a carbon number of 1 to 12, andexamples of which can include mesyl and tosyl), a sulfinyl group (whichhas preferably a carbon number of 1 to 30, more preferably a carbonnumber of 1 to 20, and most preferably a carbon number of 1 to 12, andexamples of which can include methane sulfinyl and benzene sulfinyl), anureido group (which has preferably a carbon number of 1 to 30, morepreferably a carbon number of 1 to 20, and most preferably a carbonnumber of 1 to 12, and examples of which can include ureido,methylureido, and phenylureido), an amide phosphate group (which haspreferably a carbon number of 1 to 30, more preferably a carbon numberof 1 to 20, and most preferably a carbon number of 1 to 12, and examplesof which can include diethyl amide phosphate and phenyl amidephosphate), an hydroxy group, a mercapto group, a halogen atom (examplesof which can include a fluorine atom, a chlorine atom, a bromine atom,and an iodine atom), a cyano group, a sulfo group, a carboxyl group, anitro group, a hydroxamic group, a sulfino group, a hydrazino group, animino group, a heterocyclic group (which has preferably a carbon numberof 1 to 30 and more preferably a carbon number of 1 to 12 and whichincludes, for example, a nitrogen atom, an oxygen atom, and a sulfuratom as the hetero atom, examples of which can include imidazolyl,pyridyl, quinolyl, furyl, thienyl, piperidyl, morpholino, benzoxazolyl,benzimidazolyl, benzthiazolyl, carbazolyl, and azepinyl), a silyl group(which has preferably a carbon number of 3 to 40, more preferably acarbon number of 3 to 30, and most preferably a carbon number of 3 to24, and examples of which can include trimethylsilyl andtriphenylsilyl), and a silyloxy group (which has preferably a carbonnumber of 3 to 40, more preferably a carbon number of 3 to 30, and mostpreferably a carbon number of 3 to 24, and examples of which can includemethylsilyloxy and triphenylsilyloxy). These substituent groups may besubstituted again.

R⁴¹, R⁴², R⁴³, and R⁴⁴ are preferably one of an alkyl group, an alkoxygroup, and a substituted amino group, more preferably one of an alkylgroup and a substituted amino group, and most preferably an alkyl group.

m⁴¹, m⁴², m⁴³, and m⁴⁴ represent an integer of 0 to 3, preferably one of0 and 1, and more preferably 0. When m⁴¹, m⁴², m⁴³, and m⁴⁴ are plural,the plural R⁴¹, R⁴², R⁴³, and R⁴⁴ may be equal to each other ordifferent from each other.

Hereinafter, specific examples of the compounds represented by Formulas(1), (2), (3) and (4) are described, but the present invention is notlimited to the examples.

The content of the metal complex is preferably in the range of 0.1 to 99mass % with respect to the total mass of the organic compound layer,more preferably in the range of 1 to 50 mass %, and most preferably inthe range of 3 to 20 mass %. (In this specification, mass ratio is equalto weight ratio.)

In addition, the T₁ level (energy level of the least triplet excitedstate) of the layer (such as a hole transporting layer, an electrontransporting layer, a charge carrier blocking layer, and an exciterblocking layer) contacting the organic compound layer containing themetal complex is preferably in the range of 60 Kcal/mol (251.4 KJ/mol)to 90 Kcal/mol (377.1 KJ/mol), more preferably in the range of 62Kcal/mol (259.78 KJ/mol) to 85 Kcal/mol (356.15 KJ/mol), and mostpreferably in the range of 65 Kcal/mol (272.35 KJ/mol) to 80 Kcal/mol(335.2 KJ/mol).

The metal complexes according to the present invention described abovecan be manufactured with reference to well-known methods. For example,Compound (1-1) described above can be synthesized by the use of thefollowing synthesis scheme in the same way as synthesizing Compound (79)described in page 111 of WO2004/108857 A2. Compound (1-1) may also besynthesized by converting tetrakis(N-oxopyridyl)methane, which isdescribed Tetrahedron Lett 44(2003) 2861, intotetrakis(2-bromopyridyl)methane with phosphorous oxybromide (POBr₃),coupling tetrakis(2-bromopyridyl)methane to phenylboric acid to adjusttetrakis(2-phenylpyridyl)methane (ligand), and then allowingtetrakis(2-phenylpyridyl)methane to react with platinum chloride.

The complexes can be synthesized by mixing a ligand with a metal source(for example, platinum chloride, palladium chloride, potassium platinumchloride, sodium palladium chloride, platinum bromide, and platinumacetylacetone complex) under existence or non-existence of a solvent(for example, acetonitrile, benzonitrile, acetic acid, ethanol,methoxyethanol, glycerol, water, and a mixture solvent thereof). Anadditive (for example, trifluoromethane silver sulfide) for activatingthe reaction may be added thereto, the reaction may be performed underexistence of inert gas (such as nitrogen and argon).

The reaction temperature is not particularly limited, but is preferablyin the range of −30° C. to 400° C, more preferably in the range of 0° C.to 350° C., and most preferably in the range of 25° C. to 300° C.

The method of forming the organic compound layer containing the metalcomplex is not particularly limited, and examples thereof can include aresistance heating deposition method, an electron beam method, asputtering method, a molecule deposition method, a coating method (suchas a spray coating method, a dip coating method, an impregnation method,a roll coating method, a gravure coating method, a reverse coatingmethod, a roll brush method, an air knife coating method, a curtaincoating method, a spin coating method, a flow coating method, a barcoating method, a micro gravure coating method, an air doctor coatingmethod, a blade coating method, a squeeze coating method, a transferroll coating method, a kiss coating method, a cast coating method, anextrusion coating method, a wire-bar coating method, and a screencoating method), an inkjet method, a printing method, and a transfermethod. Among them, the resistance heating deposition method, thecoating method, and the transfer method are more preferable in view ofcharacteristics and manufacturing thereof.

The organic electroluminescent device according to the present inventionhas the organic compound layer containing the metal complex as a lightemitting layer between a pair of electrodes including a positiveelectrode and a negative electrode. The organic electroluminescentdevice according to the present invention may further have a functionallayer in addition to the light emitting layer. Examples of thefunctional layer can include a hole injecting layer, a hole transportinglayer, an electron injecting layer, an electron transporting layer, aprotective layer, a charge carrier blocking layer, and an exciterblocking layer. The organic electroluminescent device according to thepresent invention preferably has at least three layers of the holetransporting layer, the light emitting layer, and the electrontransporting layer. The respective layers may have different functions.A variety of well-known materials may be used to form the respectivelayers.

The positive electrodes serves to supply holes to the hole injectinglayer, the hole transporting layer, and the light emitting layer may bemade of metal, alloy, metal oxide, electrical conductive compound, ormixtures thereof. A material having a work function of 4 eV or more ispreferable. Specific examples of the material can include conductivemetal oxide such as tin oxide, zinc oxide, indium oxide, and indium-tinoxide (ITO), metal such as gold, silver, chromium, and nickel, a mixtureor stacked material of the metal and the conductive metal oxide, aninorganic conductive material such as copper iodide and copper sulfide,an organic conductive material such as poly aniline, poly thiophene, andpoly pyrrole, and a stacked material of the materials and ITO. Theconductive metal oxide is preferable and ITO is more preferable in viewof productivity, high conductivity, and transparency.

The thickness of the positive electrode can be properly selecteddepending upon the materials, but is preferably in the range of 10 nm to5 am, more preferably in the range of 50 nm to 1 μm, and most preferablyin the range of 100 nm to 500 nm.

The positive electrode is generally used in the state that it is formedon a soda lime glass substrate, an alkali-free glass substrate, atransparent resin substrate, or the like. When a glass substrate isused, the material thereof is preferably the alkali-free glass so as toreduce the ions eluted from the glass. When the soda lime glasssubstrate is used, it is preferable that a barrier coating process withsilica is performed thereto. The thickness of the substrate is notparticularly limited so long as it is enough to maintain the mechanicalstrength thereof, but when the glass substrate is used, the thickness ofthe substrate is preferably 0.2 mm or more and more preferably 0.7 mm ormore.

A variety of methods can be used to manufacture the positive electrode.For example, when the positive electrode is made of ITO, the positiveelectrode is formed as a film by the use of an electron beam method, asputtering method, a resistance heating deposition method, a chemicalreaction method )a sol-gel method), or a method of coating a material inwhich indium-tin oxide is dispersed.

By performing a cleaning process or other processes to the positiveelectrode, the driving voltage of the device can be decreased or thelight emission efficiency thereof can be increased. For example, whenthe positive electrode is made of ITO, UV-ozone processing or plasmaprocessing is advantageous.

The negative electrode serves to supply electrons to the electroninjecting layer, the electron transporting layer, and the light emittinglayer, and the material of the negative electrode is selected inconsideration of the adhesion to a layer contacting the negativeelectrode, such as the electron injecting layer, the electrontransporting layer, and the light emitting layer, the ionizationpotential, and the stability. Examples of the material of the negativeelectrode can include metal, alloy, metal halide, metal oxide,electrical conductive compounds, and mixtures thereof. The specificexamples of the material can include alkali metal (such as Li, Na, andK) and fluoride or oxide thereof, alkali earth metal (such as Mg and Ca)and fluoride or oxide thereof, gold, silver, plumbum, aluminum,sodium-potassium alloy or mixture, lithium-aluminum alloy or mixture,magnesium-silver alloy or mixture, and rare earth metal such as indiumand yttrium. A material having a work function of 4 eV or less ispreferable, and aluminum, lithium-aluminum alloy or mixture, andmagnesium-silver alloy or mixture is more preferable. The negativeelectrode may have a single-layered structure of the compound and themixture described above, or may have a multi-layered structure includingthe compounds and the mixtures described above. A multi-layeredstructure such as aluminum/lithium fluoride and aluminum/lithium oxideis preferable.

The thickness of the negative electrode can be properly selecteddepending upon the materials, but is preferably in the range of 10 nm to5 μm, more preferably in the range of 50 nm to 1 μm, and most preferablyin the range of 100 nm to 1 μm.

The electron beam method, the sputtering method, the resistance heatingdeposition method, the coating method, the transfer method, or the likecan be used to manufacture the negative electrode. Two or more metalscan be simultaneously deposited as simplexes. In addition, an alloyelectrode may be formed by simultaneously depositing a plurality ofmetals and an alloy adjusted in advance may be deposited.

The sheet resistances of the positive electrode and the negativeelectrode are preferably low and more preferably several hundreds orless Ω/□.

Similarly to the positive electrode, the negative electrode can beprepared on a substrate. The material of the substrate is notparticularly limited, and examples thereof can include an inorganicmaterial such as zirconia-stabilized yttrium and glass, poly ester suchas poly ethyleneterephthalate, poly butylenes terephthalate, and polyethylene naphthalate, a high-molecular material such as poly ethylene,poly carbonate, poly ethersulfone, poly arylate, aryldiglycolcarbonate,poly imide, poly cycloolefin, norbornene resin, poly(chlorotrifluoroethylene), teflon, and poly tetrafluoro ethylene-poly ethylenecopolymer.

The light emitting layer may contain the metal complexes described aboveas the light emitting material.

The light emitting layer may contain a host material in addition to themetal complex described above. The host material is not particularlylimited so long as it has a function of injecting holes from thepositive electrode, the hole injecting layer, or the hole transportinglayer at the time of application of a voltage and injecting electronsfrom the negative electrode, the electron injecting layer, or theelectron transporting layer, a function of moving the injected chargecarriers, or a function of providing a place for re-coupling the holesand the electrons to emit light.

Specific examples of the host material can include a variety of metalcomplexes such as a rare earth complex or a metal complex ofbenzooxazole, benzoimidazole, benzothiazole, styrylbenzene, polyphenyl,diphenyl butadiene, tetraphenyl butadiene, naphthalimide, coumarin,perylene, perignon, oxadiazole, aldazine, pyrazine, cyclopentadiene,bisstyrylanthracene, quinacridone, pyrrolopyridine, thiadiazoropyridine,styrylamine, aromatic dimethylidine compound, and 8-quinolinol, polymercompounds such as poly thiophene, poly phenylene, and poly phenylenevinylene, transition metal complexes such as organic silane, iridiumtrisphenylpyridine complex, and platinum forpyrine complex, andderivatives thereof.

When the light emitting layer contains the host material, the content ofthe host material is not particularly limited, but it is preferable thatthe host material is a major component (the content of which islargest). The host material is preferably in the range of 51 to 99.9mass % and more preferably in the range of 70 to 99.9 mass %.

The ionization potential of the host material contained in the lightemitting layer is preferably in the range of 5.8 eV to 6.3 eV, morepreferably in the range of 5.95 eV to 6.25 eV, and most preferably inthe range of 6.0 eV to 6.2 eV.

The electron mobility of the host material contained in the lightemitting layer is preferably in the range of 1×10⁻⁶ cm²/Vs to 1×10⁻¹cm²/Vs, more preferably in the range of 5×10⁻⁶ cm²/Vs to 1×10⁻² cm²/Vs,still more preferably in the range of 1×10⁻⁵ cm²/Vs to 1×10⁻² cm²/Vs,and most preferably in the range of 5×10⁻⁵ cm²/Vs to 1×10⁻² cm²/Vs.

The hole mobility of the host material contained in the light emittinglayer is preferably in the range of 1×10⁻⁶ cm²/Vs to 1×10⁻¹ cm²/Vs, morepreferably in the range of 5×10⁻⁶ cm²/Vs to 1×10⁻² cm²/Vs, still morepreferably in the range of 1×10⁻⁵ cm²/Vs to 1×10⁻² cm²/Vs, and mostpreferably in the range of 5×10⁻⁵ cm²/Vs to 1×10⁻² cm²/Vs.

The glass transition point of the host material contained in the lightemitting layer is preferably in the range of 90° C. to 400° C., morepreferably in the range of 100° C. to 380° C., still more preferably inthe range of 120° C. to 370° C., and most preferably in the range of140° C. to 360° C.

The T₁ level (energy level of the least triplet excited state) of thehost material contained in the light emitting layer is preferably in therange of 60 Kcal/mol (251.4 KJ/mol) to 90 Kcal/mol (377.1 KJ/mol), morepreferably in the range of 62 Kcal/mol (259.78 KJ/mol) to 85 Kcal/mol(356.15 KJ/mol), and most preferably in the range of 65 Kcal/mol (272.35KJ/mol) to 80 Kcal/mol (335.2 KJ/mol).

The thickness of the light emitting layer is not particularly limited,but is preferably in the range of 1 nm to 5 μm, more preferably in therange of 5 nm to 1 μm, and most preferably in the range of 10 nm to 500nm.

The light emitting layer may have a single-layered structure or amulti-layered structure. When the light emitting layer has amulti-layered structure, the number of stacked layers is preferably inthe range of 2 to 50 layers, more preferably in the range of 4 to 30layers, and most preferably in the range of 6 to 20 layers. In thiscase, the respective layers may be made of a single material or may bemade of a plurality of compounds.

The thicknesses of the layers constituting the multi-layered structureare not particularly limited, but are preferably in the range of 0.2 nmto 20 nm, more preferably in the range of 0.4 nm to 15 nm, still morepreferably in the range of 0.5 nm to 10 nm, and most preferably in therange of 1 nm to 5 nm.

When the light emitting layer has a single-layered structure, the singlelayer may emit white light. When the light emitting layer has amulti-layered structure, the respective layers may emit light ofdifferent colors to emit, for example, white light.

The light emitting layer may have a multi-domain structure. For example,the light emitting layer may include a domain having a mixture of onehost material and the light emitting material and a domain having amixture of another host material and another light emitting material.The domain may have a volume of about 1 nm³. The size of each domain ispreferably in the range of 0.2 nm to 10 nm, more preferably in the rangeof 0.3 nm to 5 nm, still more preferably in the range of 0.5 nm to 3 nm,and most preferably in the range of 0.7 nm to 2 nm.

The method of forming the light emitting layer is not particularlylimited, and examples thereof can include a resistance heatingdeposition method, an electron beam method, a sputtering method, amolecule deposition method, a coating method, an inkjet method, aprinting method, an LB method, and a transfer method. Among them, theresistance heating deposition method and the coating method arepreferable.

The materials of the hole injecting layer and the hole transportinglayer may have any one of a function of injecting holes from thepositive electrode, a function of transporting holes, and a function ofblocking electrons injected from the negative electrode. Specificexamples thereof can include a conductive high-molecular oligomer suchas carbazole, triazole, oxazole, oxadiazole, imidazole, poly arylalkane,pyrazoline, pyrazolone, phenylenediamine, arylamine, amino-substibutedchalcone, styrylanthracene, fluorenone, hydrazone, stilbene, silazane,aromatic third-degree amine compound, styryl amine compound, aromaticJIMECHIRI DIN compound, porphyrin compound, poly silane compound,poly(N-vinylcarbazole), aniline copolymer, thiophene oligomer, and polythiophene, an organic silane, a carbon film, the compounds according tothe present invention, and derivatives thereof.

The thicknesses of the hole injecting layer and the hole transportinglayer are not particularly limited, but are preferably in the range of 1nm to 5 μm, more preferably in the range of 5 nm to 1 μm, and mostpreferably in the range of 10 nm to 500 nm. The hole injecting layer andthe hole transporting layer may have a single-layered structureincluding one or two kinds of the above-mentioned materials and may havea multi-layered structure including a plurality of layers with like ordifferent compositions.

A vacuum deposition method, an LB method, a coating method using thematerial of the hole injecting layer and the hole transporting layerdissolved or dispersed in a solvent, an inkjet method, a printingmethod, or a transfer method can be used to form the hole injectinglayer and the hole transporting layer. When the coating method is used,the material can be dissolved or dispersed along with a resin component.Examples of the resin component can include poly vinyl chloride, polycarbonate, poly styrene, poly methlymethacrylate, polybutylmethacrylate, poly ester, poly sulfon, poly phenyleneoxide, polybutadiene, poly(N-vinylcarbazole), hydrocarbon resin, ketone resin,phenoxy resin, poly amide, ethyl cellulose, vinyl acetate, ABS resin,poly urethane, melamine resin, unsaturated polyester resin, alkyd resin,epoxy resin, and silicon resin.

The materials of the electron injecting layer and the electrontransporting layer may have any one of a function of injecting electronsfrom the negative electrode, a function of transporting electrons, and afunction of blocking holes injected from the positive electrode.Specific examples thereof can include a variety of metal complexes suchas metal complexes of aromatic tetracarbonic acid anhydride such astriazole, oxazole, oxadiazole, imidazole, fluorenone,anthraquinodimethane, anthrone, diphenyl quinone, thiopyrandioxide,carbodimide, fluorenylidene methane, distyrylpyrazine, naphthalene, andperylene, phthalocyanine, and 8-quinolinol, and metal complexes havingmethalphthalocyanine, benzooxazole, or benzothiazole as a ligand, anorganic silane, and derivatives thereof.

The thicknesses of the electron injecting layer and the electrontransporting layer are not particularly limited, but are preferably inthe range of 1 nm to 5 μm, more preferably in the range of 5 nm to 1 μm,and most preferably in the range of 10 nm to 500 nm. The electroninjecting layer and the electron transporting layer may have asingle-layered structure including one or two kinds of theabove-mentioned materials and may have a multi-layered structureincluding a plurality of layers with like or different compositions.

A vacuum deposition method, an LB method, a coating method using thematerial of the electron injecting layer and the electron transportinglayer dissolved or dispersed in a solvent, an inkjet method, a printingmethod, or a transfer method can be used to form the electron injectinglayer and the electron transporting layer. When the coating method isused, the material can be dissolved or dispersed along with a resincomponent. Examples of the resin component can include the materialsexemplified for the hole injecting layer and the hole transportinglayer.

A material of the protective layer may have a function of preventing amaterial of promoting device deterioration, such as moisture and oxygen,from entering the device. Specific examples thereof can include metalsuch as In, Sn, Pb, Au, Cu. Ag, Al, Ti, and Ni, metal oxide such as MgO,SiO, SiO₂, Al₂O₃, GeO, NiO, CaO, BaO, Fe₂O₃, Y₂O₃, and TiO₂, metalfluoride such as MgF₂, LiF, AlF₃, and CaF₂, nitride such as SiN_(x) andSiO_(x)N_(y), poly ethylene, poly propylene, poly methylmethacrylate,poly imide, poly urea, poly tetrafluoroethylene, polychlorotrifluoroehtylene, poly dichlorodifluoroethylene, a copolymer ofchlorotrifluoroethylene and dichlorodifluoroethylene, a copolymerobtained by copolymerizing tetrafluoroethylene and monomer mixtureincluding at least one kind of co-monomer, fluorine-containing copolymerhaving a cyclic structure in a copolymer main chain, a water absorbingmaterial having a water absorption rate of 1% or more, and amoisture-resistant material having a water absorption rate of 0.1% orless.

The method of forming the protective layer is not particularly limited,but examples thereof can include a vacuum deposition method, asputtering method, a reactive spattering method, an MBE (molecular beamepitaxy) method, a cluster ion beam method, an ion plating method, aplasma polymerization method (high-frequency excited ion platingmethod), a plasma CVD method, a laser CVD method, a thermal CVD method,a gas source CVD method, a coating method, a printing method, and atransfer method.

The organic electroluminescent device according to the present inventionmay contain a blue fluorescent compound. Alternatively, a multi-colorlight emitting device or a full-color light emitting device may bemanufactured by simultaneously using a blue light emitting devicecontaining a blue fluorescent compound and the light emitting deviceaccording to the present invention.

In the organic electroluminescent device according to the presentinvention, the maximum wavelength of the emitted light is preferably inthe range of 390 nm to 495 nm in view of blue color purity and morepreferably in the range of 400 nm to 490 nm. The light emitting deviceaccording to the present invention may have the maximum wavelength ofthe emitted light at 500 nm or more and may be a white light emittingdevice.

In the organic electroluminescent device according to the presentinvention, the x value of CIE chromaticity of the emitted light ispreferably 0.22 or less in view of the blue color purity and morepreferably 0.20 or less. The y value of CIE chromaticity of the emittedlight is preferably 0.25 or less, more preferably 0.20 or less, and mostpreferably 0.15 or less.

In the organic electroluminescent device according to the presentinvention, the half width of an emission spectrum is preferably 100 nmor less, more preferably is 90 nm or less, still more preferably 80 nmor less, and most preferably 70 nm or less.

In the organic electroluminescent device according to the presentinvention, the external quantum efficiency is preferably 5% or more,more preferably 10% or more, and most preferably 13% or more. As thevalue of the external quantum efficiency, the maximum value of theexternal quantum efficiency when the device is driven at 20° C. may beused or the value of the external quantum efficiency when the device isdriven in the range of 100 to 300 cd/m² at 20° C. may be used.

In the organic electroluminescent device according to the presentinvention, the internal quantum efficiency is preferably 30% or more,more preferably 50% or more, and most preferably 70% or more. Theinternal quantum efficiency is calculated as “internal quantumefficiency=external quantum efficiency/light extraction efficiency.” Thelight extraction efficiency of a conventional organic EL device is about20%, but the light extraction efficiency may be set to 20% or more bydevising the shape of a substrate, the shape of an electrode, thethickness of an organic layer, the thickness of an inorganic layer, therefractive index of an organic layer, the refractive index of aninorganic layer, and the like.

In the organic electroluminescent device according to the presentinvention, the light extraction efficiency can be improved by a varietyof known devisal. For example, by processing the surface shape of asubstrate (for example, forming a micro uneven pattern), or controllingthe refractive indexes of the substrate, the ITO layer, and the organiclayer, or controlling the thickness of the substrate, the ITO layer, andthe organic layer, the light extraction efficiency can be improved,thereby enhancing the external quantum efficiency.

The organic electroluminescent device according to the present inventionmay be of a so-called top emission type, which extracts the light fromthe negative electrode (see Japanese Unexamined Patent ApplicationPublication Nos. 2003-208109, 2003-248441, 2003-257651, and2003-282261).

The system, the driving method, and the utilization type of the organicelectroluminescent device according to the present invention are notparticularly limited. A typical example of the electroluminescent deviceis an organic EL device.

The applications of the organic electroluminescent device according tothe present invention are not particularly limited, but it may be usedvery suitably for the fields such as display device, display, backlight,electronic photograph, lighting light source, recording light source,exposing light source, reading light source, signboard, interior,optical communication.

EXAMPLE

Hereinafter, specific experimental examples of the present inventionwill be described, but the present invention is not limited to thespecific experimental examples described below.

Comparative Example 1

A cleaned ITO substrate was placed into a vapor deposition apparatus andwas coated with copper phthalocyanine with a thickness of 10 nm. NPD(N,N′-di-═-naphthyl-N,N′-diphenyl-benzidine) was deposited thereon witha thickness of 20 nm. Compound (79) described in WO 2004/108857 and CBPwere deposited on the resultant structure at a ratio (mass ratio) of5:95 with a thickness of 30 nm. Then, BAlq was deposited thereon with athickness of 10 nm and Alq (tris(8-hydroxyquinoline)aluminum complex)was deposited thereon with a thickness of 40 nm. Thereafter, lithiumfluoride was deposited with a thickness of 3 nm, and then aluminum wasdeposited thereon with a thickness of 60 nm, thereby manufacturing an ELdevice. As a result of applying a DC steady voltage to the EL device toemit light by the use of Source measure unit 2400 made by ToyoCorporation, the green light could be obtained.

Example 1

By using Compound (1-1) according to the present invention instead ofCompound (79) in the EL device according to Comparative Example 1, an ELdevice was manufactured and estimated similarly to ComparativeExample 1. As a result, green light could be obtained. The half-lifeperiod of brightness of the EL device when it was driven with current of1 mA (in light emission area of 4 mm²) was 2.5 times that of the ELdevice according to Comparative Example 1.

Example 2

By using Compound (1-3) according to the present invention instead ofCompound (79) in the EL device according to Comparative Example 1, an ELdevice was manufactured and estimated similarly to ComparativeExample 1. As a result, blue-green light could be obtained. Thehalf-life period of brightness of the EL device when it was driven withcurrent of 1 mA (in light emission area of 4 mm²) was 2.1 times that ofthe EL device according to Comparative Example 1.

When the other compounds according to the present invention are used fordevices, it is possible to manufacture EL devices having excellentdurability.

According to the present invention described above, it is possible toprovide an organic electroluminescent device having at least one of highexternal quantum efficiency and high durability.

The entire disclosure of each and every foreign patent application fromwhich the benefit of foreign priority has been claimed in the presentapplication is incorporated herein by reference, as if fully set forth.

1. An organic electroluminescent device comprising: a pair ofelectrodes; and at least one organic compound layer including a lightemitting layer between the pair of electrodes, wherein the at least oneorganic compound layer contains a metal complex that has a tridentate ormore ligand and two or more metal ions.
 2. The organicelectroluminescent device according to claim 1, wherein the metalcomplex is a phosphorescent material.
 3. The organic electroluminescentdevice according to claim 1, wherein the tridentate or more ligand ofthe metal complex is a ligand in which two quadridentate ligands areconnected to each other.
 4. The organic electroluminescent deviceaccording to claim 1, wherein the two or more metal ions of the metalcomplex are selected from the group consisting of a rhodium ion, apalladium ion, a rhenium ion, a iridium ion and a platinum ion.
 5. Theorganic electroluminescent device according to claim 1, wherein themetal complex is a compound represented by Formula (1):

wherein M¹¹ and M¹² each independently represents a metal ion; Q¹¹, Q¹²,Q¹³ and Q¹⁴ each independently represents an atom group coordinatingwith M¹¹; Q¹⁵, Q¹⁶, Q¹⁷ and Q¹⁸ each independently represents an atomgroup coordinating with M¹²; L¹¹, L¹², L¹³, L¹⁴, L¹⁵ and L¹⁶ eachindependently represents a single bond or a connection group; L¹⁷represents a connection group; n¹¹ and n¹² each independently represents0 or 1, provided that when n¹¹ is 0, a bond in which L¹³ is interposedbetween Q¹³ and Q¹⁴ does not exist, and when n¹² is 0, a bond in whichL¹⁶ is interposed between Q¹⁷ and Q¹⁸ does not exist; M¹¹-Q¹¹ bond,M¹¹-Q¹² bond, M¹¹-Q¹³ bond, M¹¹-M¹⁴ bond, M¹²-Q¹⁵ bond, M¹²-Q¹⁶ bond,M¹²-Q¹⁷ bond and M¹²-Q¹⁸ bond each may be a covalent bond, a coordinatebond or an ion bond.
 6. The organic electroluminescent device accordingto claim 5, wherein the compound represented by Formula (1) is acompound represented by Formula (2) or (3):

In Formula (2), M²¹ and M²² each independently represents a metal ion;Q²¹, Q²², Q²³ and Q²⁴ each independently represents an atom groupcoordinating with M²¹; Q²⁵, Q²⁶, Q²⁷ and Q²⁸ each independentlyrepresents an atom group coordinating with M²²; L²¹, L²³, L²⁴, L²⁵ andL²⁶ each independently represents a single bond or a connection group;L²⁷ represents a connection group; n²¹ and n²² each independentlyrepresents 0 or 1, provided that when n²¹ is 0, a bond in which L²³ isinterposed between Q²³ and Q²⁴ does not exist, and when n²² is 0, a bondin which L²⁶ is interposed between Q²⁷ and Q²⁸ does not exist; M²¹-Q²¹bond, M²¹-Q²² bond, M²²-Q²⁵ bond and M²²-Q²⁶ bond (dotted line)represent coordinate bonds; and M²¹-Q²³ bond, M²¹-Q²⁴ bond, M²²-Q²⁷ bondand M²²-Q²⁸ bond each may be a covalent bond, a coordinate bond or anion bond, and in Formula (3), M³¹ and M³² each independently represent ametal ion; Q³¹, Q³², Q³³ and Q³⁴ each independently represents an atomgroup coordinating with M³¹; Q³⁵, Q³⁶, Q³⁷ and Q³⁸ each independentlyrepresents an atom group coordinating with M³²; L³¹, L³², L³³, L³⁴, L³⁵and L³⁶ each independently represents a single bond or a connectiongroup; L³⁷ represents a connection group; n³¹ and n³² each independentlyrepresents 0 or 1, provided that when n³¹ is 0, a bond in which L³³ isinterposed between Q³³ and Q³⁴ does not exist, and when n32 is 0, a bondin which L³⁶ is interposed between Q³⁷ and Q³⁸ does not exist; M³¹-Q³³bond, M³¹-Q³⁴ bond, M³²-Q³⁷ bond and M³²-Q³⁸ bond (dotted line)represent coordinate bonds; and M³¹-Q³¹ bond, M³¹-Q³² bond, M³²-Q³⁵ bondand M³²-Q³⁶ bond each may be a covalent bond, a coordinate bond or anion bond.
 7. The organic electroluminescent device according to claim 5,wherein the compound represented by Formula (1) is a compoundrepresented by Formula (4):

wherein M⁴¹ and M⁴² each independently represents a metal ion; Q⁴³ andQ⁴⁴ each independently represents an atom group coordinating with M⁴¹;Q⁴⁷ and Q⁴⁸ each independently represents an atom group coordinatingwith M⁴²; L⁴⁷ represents a connection group; R⁴¹, R⁴², R⁴³ and R⁴⁴ eachindependently represents a substituent group; m⁴¹, m⁴², m⁴³ and m⁴⁴ eachindependently represents an integer of 0 to 3; M⁴¹-N bond and M⁴²-N bond(dotted line) represent coordinate bonds; and M⁴¹-Q⁴³ bond, M⁴¹-Q⁴⁴bond, M⁴²-Q⁴⁷ bond and M⁴²-Q⁴⁸ bond each may be a covalent bond, acoordinate bond or an ion bond.